Generally, wired or wireless burglar alarms for vehicles have the following defects:
(1) The alarm must be turned on before leaving the vehicle. However, a careless driver may leave the alarm off and thus the alarm is not operating.
(2) A function test of the alarm is not possible, so it is impossible to check the alarm for any trouble or malfunction of its circuit.
(3) It is inconvenient, since the user must leave the car as soon as possible within a delay period after turning on the alarm.
(4) A signal indicating that the alarm is not operating is usually very noisy, so the user never wants to test the alarm.
(5) Repeated triggering is not possible, and the alarm becomes useless after the first sensor is activated.
In view of the above defects, the inventor has created a burglar alarm with a multi-phase circuit, a fail-safe control circuit, an automatic rearm circuit, and a two-step disarming circuit.
The present invention has a self-testing function and the following characteristics:
(1) It automatically enters a standby mode as soon as a door, engine hood, or trunk lid is opened.
(2) It automatically enters a standby mode as soon as the last door is closed.
(3) It gives a short "CHIRP" signal after the closing of the last door or engine hood or trunk lid, as an indication that the doors have been fully closed and the alarm is in operating condition (function of the fail-safe control circuit).
(4) Its sensors can trigger the alarm sequentially, so that even after one sensor has triggered the alarm, the vehicle is still protected by the other sensors.
(5) Easy to operate, without limitation from period of delay-triggering.
(6) A wireless signal can disarm the alarm only temporarily. A further disarming procedure must be completed within a preset time before the alarm is rearm automatically. Therefore, it prevents interference from other wireless signals, so a vehicle with this alarm is protected from accidental disarming as well as from burglary.